# Tag Info

20

I believe it has less to do with strength and more to do with stiffness. A rod of aluminum of the same length and weight as a a steel rod will be just as strong (force required to break) but have three times the cross-sectional area which hugely increases the second moment of inertia by nine times (it scales to the fourth power of distance/length which is ...

15

If furnished in a thin, polished sheet, aluminum will reflect infrared radiation, as for instance in a so-called "space blanket" which consists of a thin sheet of plastic on which a thin and smooth layer of aluminum has been deposited. In this context, the aluminum can prevent heat losses by reflecting infrared radiation. But if that thin sheet of ...

9

It really depends on what you are trying to do with it. And thermal "conductors" and "insulators" are not a hard and fast distinction in properties like electric conductors or insulators. Every material just has a certain thermal conductivity, so compared to say diamond, aluminum has low conductivity. With foil, wrapping it with air ...

9

TL;DR: Materials perform differently under different loading conditions. Some applications are more suited for steel others for aluminium I will try to give another more general perspective/approach, using the concept of material indices (mainly other users gave perfectly adequate explanations of the differences between bending and tension and stiffness vs ...

6

Sometimes the strength isn't required, so size for size, aluminium is lighter. e.g. bicycles often use aluminium screws to hold the bottle cage to the frame. The size of the screw is set to be comfortable to handle, and to accept the same size Allen key as other screws on the bike. But, it doesn't need to be super strong as it's not taking a critical or high ...

4

When Zeppelins were designed, only non-sparking materials were allowed for them so the hydrogen gas that invariably seeps from the gas bags would not find an ignition source. Steel did not qualify. But this is admittedly a rare example. The other answers which mention the second moment of inertia are spot-on, though. If you build a load-carrying shell you ...

3

And, in addition for sheet metal application like aircraft skin the aluminum could be 0.040 " ( 1 mm) thick ; the equal steel would be 0.013" thick . The steel would be so thin it would cause handling problems and , I expect other problems in the real world. PS ; maraging steels are good for NASA but not much use in the real world. Regular Q&T ...

3

Some engineering aspects, related to designing end products (my experience is in prototypes and small-volume production): Machining costs (accounting for time and tool wear when milling/turning) are so much less on Al alloys that the costs of extra material can be tiny in comparison - if you're starting from billets. Al is also easy to melt, so casting is ...

3

My reputation is too low to comment so I'll give some pointers in an answer :) Looking at your design your structures weak points are the areas where the plate and the sensors interface, especially the ones in the corners. This is because you have a very long lever from your load to the feet of your sensors and a very small contact area between the sensor ...

2

I am just going to go with the procedure here, and the formulas. Then I'm going to give you a numeric example. The maximum Force that a cantilever beam can support without yielding is given by ( I could go through the derivation but I don't think its relevant): $$F= \frac{2 \sigma_{allow} I}{b \cdot L}$$ where: $\sigma_{allow}$ : allowable stress $I$: ...

2

If we scale the picture the screw attaching the rod to the facia is at 1/10 the length of the rod. So it imparts 10 times the force of the rod to the siding. By eyeballing the fabric it is 8-10 square. Meaning a garden variety gust wind can generate roughly $15 \cdot 64= 1000/4 =250\text{ lbf}$ uplift at each corner. $250 \cdot 10= 2500\text{ lbf}$ on the ...

2

Using "normal" powder coating excludes the option to use a matte finish powder coating. If the service you are using for the coating has not presented to you this option, they are derelict in their business. Additionally, there are powders available, when properly applied, provide for a wrinkle finish, addressing the textured consideration in your ...

2

An adequate simplification would be to treat it as a simply supported beam (there is not much added benefit to treat it a plate). For a simply supported beam with: Length L = 37 5/8'' width w = 22 1/16'' - 2 1/2'' = 19 9/16'' (the width is at its thinness point) Assuming the load is dead center: $$M=P\cdot \frac{L}{2} = 1881.25 [lbf.in]$$ where: P is the ...

2

Wider tubes and beams are stronger against bending and less susceptible to buckling. Look up second moment of area. There is a limit to how thin you can make a tube before it becomes impossible (or very hard) to weld. With aluminium you can make much wider tubes which can still be welded. Just compare modern aluminium bicycle frames to older, high-end steel ...

1

Simple and short answer is it depends where do you want to use Steel or Aluminum, and what is your target. If your target is to use a material so that it will not suffer from any plastic failure or fracture when subjected to extreme loading conditions, then you have to choose a material which will have higher yield and tensile strengths (that is why steel ...

1

Aluminum has a couple of favorite properties. rust resistant. easy to extude decent strength its ideal for uses where one needs decent strength combined with light weight but enough meet to paroved space for drilling bolt into to attach brackets and or other parts. Engine block is a good example. Aluminum windows and shelving is another one. they strong ...

1

If you are not stuck on powdercoating, there are "hammered metal" paints. Rust-oleum rattle cans

1

Aluminum is usually melted in a protective atmosphere to reduce oxidation ; even more important with the Mg alloy content. Melting and casting aluminum is not a good backyard project. A charcoal bed on top of the melt and the right flux would make it possible although strength is likely to be reduced by loss of Mg. You would need to research the flux and ...

1

Can you melt 5083 and cast it? yes, this alloy is ok for this role. It is not heat treated, it has somewhat good protection against environment. I worry more about thin shell casting problem - metal may start to solidify in place before filling the mold with a size of a boat fully. Especially if you plan partial fill, using several pouring steps. And I ...

1

What's acceptable will depend on your application. For a chair, 1mm of deflection will not be noticeable. For a CNC machine not so much. If you really care about optimizing the design, I would start by designing the object with narrow extrusions, and then see if/were the deflection will be too great, then bulk it up as necessary. This calculator ...

1

In general the acceptable deflection has to do with perception. What I mean by that is, if it is possible to perceive the deflection of the structure. Therefore it is usually presented in building codes (usually that's where you most see it), as a percentage of the span of the beam. However, there is no universally accepted allowable deflection. For example: ...

1

The easiest way to maintain water resistance is to not puncture the enclosure. It looks like the box has holes extending through the cover down to the bottom, I'm guessing these are specifically for mounting? (The 2 large holes). Use those if you can. The next best option would be to attach the box so that the bottom is against the plate, and screws come in ...

1

You just need to calculate the hoop stress of a cylinder. The formula is really easy: $$\sigma =\frac{p r}{t}$$ where: $\sigma$: is the hoop stress $p$: the pressure $r= d/2$ : the radius of the tube (I would ignore the ovality if its small) $t$: the thickness of the tube.

1

I'm not an engineer by any stretch of anyone's imagination, but I have 30 years in aluminum extrusion. In the conditions you have, I would agree with going to steel. You probably have a 6063 T6 tube. With the amount of force generated by wind, you'll have enough cold-work in the aluminum to make it brittle, then it'll simply snap. If you're dead-set on ...

1

The question is "how much wind force is developed here". Depends on size and design of awning and wind conditions. An awning is similar to an aircraft wing which develops a high force. It would be stronger if the bar were attached with a brace over it rather than a couple screws through it ; the holes made stress concentrators/weak points. The next ...

1

Small very sharp teeth, hard blade, not too fast or the blade will flex, using wax was a good idea or plenty of lubricant. Make sure the blade is cutting perfectly square or you'll be chasing your tail. I'm the QM at an aluminum extruder (30 years), we cut millions of lbs a year (6xxx & 3xxx alloys). We have always used a lubricant called Boelube, made ...

1

If the extruder has a die in the exact shape you're wanting, it might be worth asking them. If you can get past the extruder's quote filter (our's is at hundreds of thousands of pounds per year), if they don't have a die for the part you're wanting, you'll be buying an extrusion die (think $3k -$6k). Do you want close tolerancing, that'll be extra. ...

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Eddy current analysis, we paid \$17k per unit, but they're for manufacturing lines. I'm not sure how much a smaller hand-held unit with a stylus-type probe is. We buy our equipment from Magnetic Analysis Corp. but I don't know if they have the smaller equipment.

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I don't know how to calculate it, but you're going to need something like a 6063 T9; it's drawn then aged. But as Chris states below, it's the yield strength that you need a lot of. It might need to be something in the 7xxx series, or also as below, something in a composite.

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There are some smaller extruders out there. You say less than .4", the standard OD's should be easy to find (.188", .250" and .375"). If you're needing something other than those, it's going to get pricey quick. Our biggest customers get the biggest price break, but those are major tier 1 automotive parts suppliers ordering 5 million+ ...

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